Three people were killed and one person was seriously injured when an oncoming train slammed into their car at a level crossing in Thailand.

The driver, an off-duty policeman, and two of his female passengers were killed after their vehicle collided with a train at the crossing in Hua Hin district, Prachuap Khiri Khan province early Thursday morning.

Another car passenger was severely hurt but survived the crash.

Security footage taken at the crash site shows a white sedan driving around the lowered barrier and rolling onto the tracks while the red light was flashing.

The roaring train, which was heading to Bangkok from Nakhon Sri Thammarat, then smashed into its side and dragged it across the railway.

The car was overturned and crumpled after the accident, with the three victims pronounced dead at the scene.

The casualties were identified as Hua Hin policeman Wara Buapharangsi, 39, Arena Chatchawan, 25, and Supawaphee Thianphanthor, 25.

The survivor, Amirun Gubu, 21, was rushed to a hospital after he was pulled from the wreckage.

The train's engine was also damaged, and its passengers had to be transferred.

Police Lieutenant Thanetphon Sermphong, deputy investigation chief of the Hua Hin police, said: 'The crash happened at the Soi Hua Hin 94 crossing at around 4 am. The four people were coming home from a party, but the driver did not notice the oncoming train.'

Police are currently investigating the accident.

Under Section 62 of Thailand's Road Traffic Act, drivers at a level crossing are required to stay at least five metres away from an oncoming train during a red light.